The purpose of this study is to investigate the function of the 3' terminus of both AA-tRNA and peptidyl-tRNA in ribosomal protein synthesis and to study the properties and functions of the ribosomal recognition sites involved in binding in the 3' terminus of AA-tRNA and peptidyl-tRNA. The chemical syntheses of 2'(3')-0-aminoacyl, 2'(3')-0-(N-acylaminoacyl) and 2'(3')-0-peptidyl oligoribonucleotides having different chain lengths, base sequences and amino acids will be undertaken, and these compounds will be used to study the substrate specificity or ribosomal peptidyl transferase at the A and P sites. The biochemical studies will be carried out using several ribosomal transfer and binding systems. The substrate specificity of certain antibiotics that inhibit protein biosynthesis will also be investigated. BIBLIOGRAPHIC REFERENCES: A.M. Bobst, and S. Chladek. Spectroscopic Properties of Various 2'(3')-0-Aminoacyldinucleoside Phosphates Analogous to the 3' Terminus of AA-tRNA. Nucleic Acids Research 3, 63 (1976). David Ringer, S. Chladek and James Ofengand. Enzymatic Binding of Amino-acyl Transfer Ribonucleic Acid to Ribosomes: The Study of Binding Sites of 2' and 3' Isomers of Aminoacyl Transfer Ribosome Acids. Biochemistry 15, in press (1976).